classification of heat exchangers p m v subbarao professor mechanical engineering department i i t...

Classification of Heat Exchangers

P M V SubbaraoProfessor

Mechanical Engineering Department

I I T Delhi

Creation of Variety in Anatomy of Heat Exchanger!!!

Time /Space Sharing

Real Need : Cool or heat a Fluid

Auxiliaries : Solid Surface & Another fluid (plentiful)

Essential : Some source of Energy (Motive Power)

More Green Methods…..

Traditional Egyptian architecture in Ancient Egypt as demonstrated on the Pharonic house of Neb- Ammun, Egypt,

19th Dynasty, c.1300 BC.

Persian: بادگیر bâdgir: bâd "wind" + gir "catcher“

Arabic: ملقف malqaf

Eastern Arabia:بارجيل barjeel

Windcatcher (Bagdir)

Degree of Greenness

Geometrical Ideas for Classification

Regenerators

Relative Direction of Flows

Scalar HX to Vector Hx

Economy of Metal Usage

dido Di

Geometrical Modifications for Better Economy

Expenditure in A Heat Exchanger

• The capital investment on Heat exchanger material is proportional to double the Heat transfer Area.

• Investment on both cold side and hot side of a heat exchanger for a given surface area of heat exchanger.

• Another expenditure is running cost or operational cost.• Main operation cost is pumping power cost.• This again increases the size of the pump and capital cost.• This arises a question of inner and outer flow pressure

drop calculations and a suitable innovation for the same.• Engineering world is like an incandescent lamp.

Two inner tubes and one outer tube

inhh Tm , & outhh Tm , &

incc Tm , &

outhc Tm , &

1cT

2cThT

Differential Element Analysis

dz

1cdT

hdT1Q2Q

2cdT

1,1 ccpcold dTcmQ

2,2 ccpcold dTcmQ

11,1 chccpcold TTUadzdTcmQ

22,2 chccpcold TTUadzdTcmQ

11,

chccpcold TT

dz

dT

Ua

cm

22,

chccpcold TT

dz

dT

Ua

cm

Heat lost by hot fluid:

2121, chchhhphot TTTTUadzQQdTcm

21, 2 cchhhphot TTTUadzdTcm

21, 2 cch

hhphot TTTdz

dT

Ua

cm

11,

chccpcold TT

dz

dT

Ua

cm

22,

chccpcold TT

dz

dT

Ua

cm